Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, 610041, China.
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 610031, China.
Sci Rep. 2022 Mar 7;12(1):3654. doi: 10.1038/s41598-022-07780-6.
This study proposed that the dissolution of calcium and magnesium minerals in river sediment could sequester CO and function as a carbon sink. Based on the published study, "the contents and chemical and mineral compositions of the suspended particulate materials in the Yangtze River and their geological environmental implications" by Ding Tiping, the contents of CaO, MgO, calcite and dolomite in suspended sediment collected from 25 sampling points in the mainstream and 13 sampling points in the tributaries of the Yangtze River in 4 sampling campaigns during 2003-2007 were used to calculate the total inorganic carbon sink (TCS) capacity and nonsubstantial and substantial inorganic carbon sink (NSCS and SCS) capacities of suspended sediment along the river. Due to the reduction in the sediment yield, the TCS, NSCS and SCS of the Cuntan-Datong section during 2006-2019 decreased by 18.52 × 10 tons, 12.24 × 10 tons and 8.72 × 10 tons, respectively, compared to the period before 2002. The average annual sedimentation of the Three Gorges Reservoir (TGR) was 114.5 × 10 tons, and the related TCS and SCS losses were 6.76 × 10 tons and 2.29 × 10 tons, respectively, which were equivalent to 7.9 and 2.7 percent of the 85.8 × 10 tons of CO emissions reduced by the clean energy production of the Three Gorges Hydropower Station. The TCS of global rivers was estimated as 757 × 10 tons (the SCS was more than one quarter of the TCS), which is equivalent to 71.6% of the TCS by global rock weathering with 1.06 × 10 tons of sequestered CO. The collision and erosion of river sediment caused by turbulence in the processes of sediment transport (off-site rock weathering) could promote the dissolution of minerals. Therefore, it is reasonable that the dissolution rate of calcium and magnesium minerals for offsite rock weathering was much higher than that for in situ rock weathering.
本研究提出，河底沉积物中钙镁矿物的溶解可以固定 CO 并起到碳汇的作用。基于已发表的研究成果，即丁悌平的《长江流域悬浮物物质的含量、化学和矿物组成及其地质环境意义》一文，该研究使用了 2003 年至 2007 年期间 4 次采样活动中在长江干流 25 个采样点和支流 13 个采样点采集的悬浮沉积物中 CaO、MgO、方解石和白云石的含量，计算了沿江水体悬浮沉积物的总无机碳汇（TCS）容量以及非实质性和实质性无机碳汇（NSCS 和 SCS）容量。由于泥沙产沙量减少，2006 年至 2019 年，寸滩-大通段的 TCS、NSCS 和 SCS 分别减少了 18.52×10 吨、12.24×10 吨和 8.72×10 吨，与 2002 年之前相比。三峡水库（TGR）的年平均淤积量为 114.5×10 吨，相关的 TCS 和 SCS 损失分别为 6.76×10 吨和 2.29×10 吨，分别相当于三峡水电站清洁能源生产减少的 85.8×10 吨 CO 排放量的 7.9%和 2.7%。全球河流的 TCS 估计为 757×10 吨（SCS 超过 TCS 的四分之一），相当于全球岩石风化 TCS 的 71.6%，与 1.06×10 吨封存的 CO 量相当。泥沙输移过程中紊流引起的河流泥沙碰撞和侵蚀（异地岩石风化）可以促进矿物溶解。因此，异地岩石风化中钙镁矿物的溶解速率远高于原地岩石风化的溶解速率是合理的。
